Computer tomography assisted stereotactic surgery system and method

Abstract

Diagnostic mapping data representing a series of planar slices through a patient are generated by a CT or other multi-plane scanner (A) and stored in an image memory (32). To free the CT or other scanner for other patients, the mapping data and patient are transferred to a second location. At the second location, the patient is restrained in a digital radiographic imaging apparatus (B) in which data representing a shadowgraphic image is generated and stored in a reference memory (60). The transferred mapping data is stored in a second image memory (32') at the second site. A shadowgraphic image synthesizer (70) synthesizes an analogous shadowgraphic image from the diagnostic mapping data in the second image memory taken relative to a selected spatial position and angular orientation. The reference and synthesized shadowgraphic images are superimposed or otherwise concurrently displayed on a video display (64). The spatial position and angular orientation from which the synthesized image is projected are adjusted until an optimal match between the superimposed images is achieved. In this manner, the current actual position of the patient and the diagnostic data in the second image memory are brought into registration. From images representing slices through the patient reconstructed from data in the image memory, the physician plans a point of entry and path through the patient which a surgical instrument (100) is to follow. A surgical instrument guide (90) is positioned such that the surgical instrument enters the patient at the coordinates at the selected point of entry and follows the selected path.

Having thus described the preferred embodiment, the invention is now claimed to be: 
     
       1. A clinical method in which a surgical instrument is precisely positioned relative to an internal region of the subject in advance of an invasive procedure, the method comprising: imaging a volume of the subject to locate a structure within the subject precisely and producing three dimensional diagnostic mapping data indicative thereof;   transferring the subject to a clinical treatment station at which the invasive procedure is to be performed, imaging the patient to relocate the structure within the patient relative to the treatment station by generating a two dimensional calibration reference image through the imaged volume that includes the structure prior to instituting the invasive procedure;   configuring an analogous two dimensional image from the three dimensional diagnostic mapping data;   comparing the calibration reference and diagnostic data two dimensional images to determine the relative orientation between the patient and the three dimensional mapping data; and,   in accordance with the comparing step, moving and orienting the surgical instrument to position the surgical instrument relative to the imaged volume for invasive treatment of the located structure.   
     
     
       2. The method as set forth in claim 1 further including generating a series of planar slice images generated from the mapping data and selecting a point of entry into the subject and a path through the patient for the invasive procedure from the planar slice images. 
     
     
       3. The method as set forth in claim 2 further including at the clinical treatment station prior to the two dimensional calibration reference image generating step, fixing the position of the surgical instrument relative to the subject such that the surgical instrument is constrainable to enter the subject through the selected point of entry and follow the selected path through the subject. 
     
     
       4. The method as set forth in claim 3 further including inserting the surgical instrument through the entrance site and along the selected path of the subject. 
     
     
       5. The method as set forth in claim 4 wherein the instrument insertion step is performed automatically with a robotic arm arrangement which carries the surgical instrument. 
     
     
       6. The method as set forth in claim 1 wherein the step of imaging a volume includes scanning the subject with a computed tomographic scanner and generating a series of planar images from the mapping data. 
     
     
       7. The method as set forth in claim 1 wherein the step of generating a two dimensional calibration reference image includes examining the subject with a digital radiographic imaging apparatus wherein the two dimensional calibration reference image is a calibration reference shadowgraphic projection image and wherein the configuring step includes configuring an analogous projection image from the diagnostic mapping data. 
     
     
       8. The method as set forth in claim 7 wherein the comparing step includes superimposing the calibration reference shadow graphic projection and the analogous diagnostic data projection images in a common display. 
     
     
       9. A clinical method in which an internal region of a subject is precisely located in advance of an invasive procedure, the method comprising: imaging a volume of the subject at a first location and producing three-dimensional diagnostic mapping data indicative thereof;   at a second location in which the invasive procedure is to be performed, imaging the subject to generate a two dimensional calibration reference image through a region of interest prior to instituting the invasive procedure, the step of generating a two dimensional calibration reference image including examining the subject with a digital radiographic imaging apparatus such that the two dimensional calibration reference image is a calibration reference shadowgraphic projection image;   projecting a projection image from the three-dimensional diagnostic mapping data which projection image is analogous to the two dimensional calibration reference image;   comparing the calibration reference image and the analogous projection image; and,   adjusting spatial position and angular orientation through which the mapping data is projected into the analogous projection image until a selected portion of the analogous projection image most accurately matches a corresponding selected portion of the calibration reference image, whereby the mapping data is brought into at least partial registration with the actual, current position of the subject.   
     
     
       10. In a clinical procedure wherein an internal region of the subject is subjected to an invasive procedure, precisely locating and mapping said internal region in advance of the procedure comprising the steps of: conducting a series of planar scans of the subject and obtaining three-dimensional electronic mapping data indicative of internal structure of at least said internal region of the subject from the scans;   generating man-readable images from the mapping data and identifying the internal region to be treated by the invasive procedure from the man-readable images;   selecting a point of entry into the subject and a path through the subject from the man-readable images;   fixing the position of the subject relative to a clinical station where the invasive procedure is to be performed;   performing a non-invasive imaging of the patient to produce a first calibration reference image representing a two dimensional shadowgraph of a least a portion of the subject along a first direction which includes said internal region;   generating analogous shadowgraphic projection image from the three-dimensional electronic mapping data which analogous shadowgraphic projection image represents a projection through the three-dimensional electronic mapping data along a calibration direction that substantially matches the first direction;   comparing the calibration reference and three-dimensional electronic mapping shadowgraphic images to obtain an indication of the location of said internal region in relation to the clinical station;   positioning an invasive instrument guide to aim a surgical instrument to enter the subject at the selected point of entry and follow the selected path; and,   producing a second calibration reference image of the guide and the subject to check to guide positioning.   
     
     
       11. An apparatus for performing an invasive surgical procedure on a subject, the apparatus comprising: scanning means for scanning at least a selected region of the subject and generating an electronic mapping data representing a three dimensional region of the subject;   an image memory means for storing the mapping data;   a display means for displaying man-readable diagnostic images reconstructed from the mapping data in the image memory, which diagnostic images represent slices through the region of interest;   an imaging means for generating and storing electronic data representative of a two dimensional reference image through the region of interest, the imaging means being operatively connected with the display means for displaying a man-readable two dimensional reference image from the stored data;   a reformatting means for reformatting the mapping data from the image memory into a reformatted diagnostic image of the format of the reference image from the imaging means;   an adjusting means for adjusting spatial position and angular orientation with which the reformatting means reformats the mapping data such that the reformatted image more closely matches the reference image; and,   a surgical instrument positioning means for positioning a surgical instrument relative to the patient to direct the surgical instrument to penetrate the patient at an entrance point selected from the diagnostic images, after generation of the images, and proceed along a path selected from the diagnostic images.   
     
     
       12. The apparatus as set forth in claim 11 further including a portable electronic data storage means which is operatively connected with the image memory means for receiving and storing the mapping data therefrom and which means is transportable to another image memory for transferring the mapping data thereto. 
     
     
       13. The apparatus as set forth in claim 11 wherein the imaging means is a digital radiographic imaging means and the reference image is a shadowgraphic projection image. 
     
     
       14. The apparatus as set forth in claim 13 wherein the reformatting means includes means for reformatting a shadowgraphic projection from the mapping data which is analogous to the reference shadowgraphic projection images of the digital radiographic imaging means such that the reformatted image represents a shadowgraphic projection and wherein the adjusting means adjusts the spatial position and angular orientation with which the projections are reformatted, whereby the orientation and position of the reformatted shadowgraphic image is adjustable until it most accurately matches the reference shadowgraphic image. 
     
     
       15. The apparatus as set forth in claim 14 further including a superimposing means for combining the reformatted and reference shadowgraphic images to facilitate comparison thereof. 
     
     
       16. The apparatus as set forth in claim 11 wherein the scanning means is a computerized tomographic scanner. 
     
     
       17. The apparatus as set forth in claim 11 wherein the surgical instrument positioning means includes an arm arrangement and a control means for robotically controlling the arm arrangement.